U.S. patent number 10,288,396 [Application Number 16/129,068] was granted by the patent office on 2019-05-14 for non-jacketed bullet and method of manufacturing a non-jacketed bullet.
This patent grant is currently assigned to Continuous Metal Technology, Inc.. The grantee listed for this patent is Continuous Metal Technology, Inc.. Invention is credited to Timothy G. Smith.
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United States Patent |
10,288,396 |
Smith |
May 14, 2019 |
**Please see images for:
( Certificate of Correction ) ** |
Non-jacketed bullet and method of manufacturing a non-jacketed
bullet
Abstract
A non-jacketed bullet including a monolithic sintered body and a
sintered projectile tip. The monolithic sintered body includes a
base portion and a deformed hollow nose portion, and the sintered
projectile tip includes a base portion and a nose portion. A
portion of the sintered projectile tip extends into the deformed
hollow nose portion of the monolithic sintered body and a portion
of the sintered projectile tip extends from a distal end of the
deformed hollow nose portion of the monolithic sintered body. Also,
a method of manufacturing a non-jacketed bullet including providing
a monolithic sintered body including a base portion and a hollow
peripheral portion providing a sintered projectile tip, inserting a
portion of the sintered projectile tip into the hollow portion of
the monolithic sintered body, and forming the hollow peripheral
portion into the shape of a hollow tapered nose.
Inventors: |
Smith; Timothy G. (St. Marys,
PA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Continuous Metal Technology, Inc. |
Ridgway |
PA |
US |
|
|
Assignee: |
Continuous Metal Technology,
Inc. (Ridgway, PA)
|
Family
ID: |
60330012 |
Appl.
No.: |
16/129,068 |
Filed: |
September 12, 2018 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20190003809 A1 |
Jan 3, 2019 |
|
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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15664282 |
Jul 31, 2017 |
10107605 |
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15407047 |
Jan 16, 2017 |
10209045 |
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62279082 |
Jan 15, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F42B
12/34 (20130101); F42B 12/74 (20130101) |
Current International
Class: |
F42B
12/00 (20060101); F42B 12/74 (20060101); F42B
12/34 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Klein; Gabriel J.
Attorney, Agent or Firm: The Webb Law Firm
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This application is continuation of U.S. patent application Ser.
No. 15/664,282 filed on Jul. 31, 2017, which is a
continuation-in-part of U.S. patent application Ser. No. 15/407,047
filed on Jan. 16, 2017, which claims priority to U.S. Provisional
Application No. 62/279,082 filed on Jan. 15, 2016, the disclosures
of which are hereby incorporated in their entirety by reference.
Claims
The invention claimed is:
1. A bullet, comprising: a monolithic sintered body comprising: a
base portion having a proximal end and a distal end; and a deformed
hollow nose portion extending distally from the distal end of the
base portion; and a sintered projectile tip comprising: a base
portion having a proximal end and a distal end; and a nose portion
extending distally from the distal end of the base portion, wherein
a portion of the sintered projectile tip extends into the deformed
hollow nose portion of the monolithic sintered body and a portion
of the sintered projectile tip extends from a distal end of the
deformed hollow nose portion of the monolithic sintered body and
wherein the bullet is non-jacketed and expandable, and the deformed
hollow nose portion is ductile such that, upon impact, the deformed
hollow nose portion expands to form distinct petals.
2. The bullet of claim 1, wherein at least one of the monolithic
sintered body and the sintered projectile tip comprise particles of
a first metal and particles of a second metal and the particles of
the first metal are bonded to the particles of the second metal by
intermetallic compounds comprising the first metal and the second
metal.
3. The bullet of claim 1, wherein at least one of the monolithic
sintered body and the sintered projectile tip comprise metallic
particles that are connected by solid state bonds formed by
compression and heat.
4. The bullet of claim 1, wherein the porosity of the bullet is
5-10%.
5. The bullet of claim 1, wherein the monolithic sintered body and
the projectile tip are lead free.
6. The bullet of claim 1, wherein the monolithic sintered body
comprises at least one of copper, nickel, tin, zinc, or any
combination thereof.
7. The bullet of claim 1, wherein the monolithic sintered body
comprises copper or a copper-based alloy.
8. The bullet of claim 1, wherein the projectile tip comprises
iron.
9. The bullet of claim 8, wherein the projectile tip comprises at
least one of carbon, molybdenum, and copper.
10. Ammunition, comprising: a bullet according to claim 1; and a
cartridge casing holding the bullet.
11. A method of manufacturing a bullet according to claim 1, the
method comprising: providing a monolithic sintered body comprising:
a base portion having a proximal end and a distal end; and a hollow
peripheral portion extending distally from the distal end of the
base portion; providing a sintered projectile tip comprising: a
base portion having a proximal end and a distal end; and a nose
portion extending distally from the distal end of the base portion;
inserting the base portion of the sintered projectile tip into the
hollow portion of the monolithic sintered body; forming the hollow
peripheral portion into a shape of a hollow tapered nose while
enclosing the base portion of the projectile tip within the hollow
portion of the monolithic sintered body; wherein a portion of the
sintered projectile tip extends into the deformed hollow nose
portion of the monolithic sintered body and a portion of the
sintered projectile tip extends from a distal end of the deformed
hollow nose portion of the monolithic sintered body and wherein the
bullet is non-jacketed and expendable, and the deformed hollow nose
portion is ductile such that, upon impact, the deformed hollow nose
portion extends to form distinct petals.
12. The method of claim 11, wherein providing the monolithic
sintered body comprises: providing a compacted powder preform
comprising: a base portion having a proximal end and a distal end;
and a hollow peripheral portion extending distally from the distal
end of the base portion; and sintering the compacted powder
preform.
13. The method of claim 11, wherein providing the projectile tip
comprises: providing a compacted powder preform comprising: a base
portion having a proximal end and a distal end; and a nose portion
extending distally from the distal end of the base portion; and
sintering the compacted powder preform.
14. The method of claim 12, wherein providing the compacted powder
preform includes: providing a powder to a cavity formed in a die
between at least an upper punch and a lower punch; and pressing the
upper and lower punches together to compact the powder.
15. The method of claim 13, wherein providing the compacted powder
preform includes: providing a powder to a cavity formed in a die
between at least an upper punch and a lower punch; and pressing the
upper and lower punches together to compact the powder.
16. The method of claim 11, wherein the monolithic sintered body
and the projectile tip are lead free.
17. The method of claim 11, wherein the monolithic sintered body
comprises at least one of copper, nickel, tin, zinc, or any
combination thereof.
18. The method of claim 11, wherein the monolithic sintered body
comprises copper or a copper-based alloy.
19. The method of claim 11, wherein the projectile tip comprises
iron.
20. The method of claim 11, wherein the projectile tip comprises at
least one of carbon, molybdenum, and copper.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates generally to non-jacketed bullets, and in
particular, to non-jacketed bullets capable of being manufactured
from lead-free materials, as well as methods of manufacturing such
non-jacketed bullets.
Description of Related Art
The use of lead-based ammunition has been increasingly regulated in
many states and countries. New, more restrictive lead bans have
placed an emphasis on developing new lead-free projectiles and
ammunition that represent cost-effective alternatives as compared
to those that are presently available. In some cases, the
implementation of regulations may be conditioned on the
availability of cost-effective alternatives to lead-free
projectiles.
Such lead projectiles and some lead-free projectiles are jacketed.
In such jacketed projectiles, a casing of hard material surrounds
the softer lead or lead-free solid projectile. Manufacturing of
such jacketed projectiles involves many drawing and annealing steps
to form a hollow cylinder made of the jacket material and then
further processing is required to form the cylinder of jacket
material around the lead or lead-free solid projectile. As such,
the manufacturing process for these projectiles can be expensive
and time consuming.
Therefore, there is a need for a non-jacketed projectile that can
be made with a simpler manufacturing process at a reduced cost, and
particularly, for a lead-free non-jacketed projectile that can be
made in a cost effective manner.
SUMMARY OF THE INVENTION
The present invention is directed to an improved non-jacketed
bullet and a method of manufacturing such a bullet. In one
preferred and non-limiting embodiment or aspect, the improved
non-jacketed bullet and the method of manufacturing the bullet
address and/or overcome certain deficiencies and drawbacks
associated with existing bullets and manufacturing processes by
providing more efficient use of raw materials and/or reducing the
number and/or difficulty of the processing steps in order to
provide a cost-effective alternative to lead-based ammunition.
The present invention is directed to an improved non-jacketed
bullet and a method of manufacturing such a bullet. In one
non-limiting embodiment or aspect, the invention is directed to a
non-jacketed bullet, comprising a monolithic sintered body and a
sintered projectile tip. The base portion has a proximal end and a
distal end and a deformed hollow nose portion extending distally
from the distal end of the base portion, the sintered projectile
tip has a base portion having a proximal end and a distal end and a
nose portion extending distally from the distal end of the base
portion. A portion of the sintered projectile tip extends into the
deformed hollow nose portion of the monolithic sintered body and a
portion of the sintered projectile tip extends from a distal end of
the deformed hollow nose portion of the monolithic sintered
body.
In one non-limiting embodiment or aspect, at least one of the
monolithic sintered body and the sintered projectile tip may
comprise particles of a first metal and particles of a second metal
and the particles of the first metal are bonded to the particles of
the second metal by intermetallic compounds comprising the first
metal and the second metal. In one non-limiting embodiment or
aspect, at least one of the monolithic sintered body and the
sintered projectile tip may comprise metallic particles that are
connected by solid state bonds formed by compression and heat.
In one non-limiting embodiment or aspect, the porosity of the
bullet may be 5-10%.
In one non-limiting embodiment or aspect, the monolithic sintered
body and the projectile tip may be lead free. In one non-limiting
embodiment or aspect, the monolithic sintered body may comprise at
least one of copper, nickel, tin, zinc, or any combination thereof.
In one non-limiting embodiment or aspect the monolithic sintered
body may comprise copper or a copper-based alloy. In one
non-limiting embodiment or aspect, the projectile tip may comprise
iron. In one non-limiting embodiment or aspect, the projectile tip
may comprise at least one of carbon, molybdenum, and copper.
In one non-limiting embodiment or aspect, the invention is directed
to ammunition comprising a non-jacketed bullet according to one or
more of the embodiments or aspects described above and a cartridge
casing holding the non-jacketed bullet.
In one non-limiting embodiment or aspect, the present invention is
directed to a method of manufacturing a non-jacketed bullet, the
method comprising providing a monolithic sintered body comprising a
base portion having a proximal end and a distal end and a hollow
peripheral portion extending distally from the distal end of the
base portion; providing a sintered projectile tip comprising a base
portion having a proximal end and a distal end and a nose portion
extending distally from the distal end of the base portion;
inserting the base portion of the sintered projectile tip into the
hollow portion of the monolithic sintered body; and forming the
hollow peripheral portion into a shape of a hollow tapered nose
while enclosing the base portion of the projectile tip within the
hollow portion of the monolithic sintered body.
In one non-limiting embodiment or aspect, the provision of the
monolithic sintered body may comprise providing a compacted powder
preform a base portion having a proximal end and a distal end and a
hollow peripheral portion extending distally from the distal end of
the base portion and sintering the compacted powder preform. In one
non-limiting embodiment or aspect, the provision of the sintered
projectile tip may comprise providing a compacted powder preform a
base portion having a proximal end and a distal end and a hollow
peripheral portion extending distally from the distal end of the
base portion and sintering the compacted powder preform. In one
non-limiting embodiment or aspect, the provision of the compacted
powder preform for the monolithic sintered body or the sintered
projectile tip comprises providing powder to a cavity formed in a
die between at least an upper punch and a lower punch and pressing
the upper and lower punches together to compact the powder.
The non-jacketed bullet produced according to the method may have
any of the aspects described above.
The present invention is neither limited to nor defined by the
above summary. Rather, reference should be made to the claims for
which protection is sought with consideration of equivalents
thereto.
These and other features and characteristics of the present
invention, as well as the methods of operation and functions of the
related elements of structures and the combination of parts and
economies of manufacture, will become more apparent upon
consideration of the following description and the appended claims
with reference to the accompanying drawings, all of which form a
part of this specification, wherein like reference numerals
designate corresponding parts in the various figures. It is to be
expressly understood, however, that the drawings are for the
purpose of illustration and description only and are not intended
as a definition of the limits of the invention. As used in the
specification and the claims, the singular form of "a", "an", and
"the" include plural referents unless the context clearly dictates
otherwise.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a non-jacketed bullet according to
a non-limiting embodiment or aspect of the present invention;
FIG. 2 is a sectional perspective view of the non-jacketed bullet
of FIG. 1;
FIG. 3 is a sectional perspective view of a non-jacketed bullet
according to a non-limiting embodiment or aspect of the present
invention;
FIG. 4A is a perspective view of a monolithic sintered body with an
internal cavity having a circular transverse cross-section before
deformation according to a non-limiting embodiment or aspect of the
present invention;
FIG. 4B is a sectional perspective view of the monolithic sintered
body of FIG. 4A;
FIG. 5A is a perspective view of a monolithic sintered body with an
internal cavity having a triangular transverse cross-section before
deformation according to a non-limiting embodiment or aspect of the
present invention;
FIG. 5B is a sectional perspective view of the monolithic sintered
body of FIG. 5A;
FIG. 6A is a perspective view of a monolithic sintered body with an
internal cavity having a square transverse cross-section before
deformation according to a non-limiting embodiment or aspect of the
present invention;
FIG. 6B is a sectional perspective view of the monolithic sintered
body of FIG. 6A;
FIG. 7A is a perspective view of a monolithic sintered body with an
internal cavity having a hexagonal transverse cross-section before
deformation according to a non-limiting embodiment or aspect of the
present invention;
FIG. 7B is a sectional perspective view of the monolithic sintered
body of FIG. 7A;
FIG. 8A is a perspective view of a monolithic sintered body with an
internal cavity having an octagonal transverse cross-section before
deformation according to a non-limiting embodiment or aspect of the
present invention;
FIG. 8B is a sectional perspective view of the monolithic sintered
body of FIG. 8A;
FIG. 9 is a sectional view of a monolithic sintered body with an
internal cavity having two portions before deformation according to
a non-limiting embodiment or aspect of the present invention;
FIG. 10 is a sectional view of tooling for forming a compacted
powder preform according to a non-limiting embodiment or aspect of
the present invention;
FIG. 11 is a sectional perspective view of tooling for forming a
compacted powder preform according to another non-limiting
embodiment or aspect of the present invention;
FIG. 12 is a sectional perspective view of tooling for forming a
compacted powder preform according to another non-limiting
embodiment or aspect of the present invention;
FIG. 13 is a sectional view of a sizing/forming press according to
a non-limiting embodiment or aspect of the present invention;
FIG. 14 is a perspective view of a non-jacketed bullet according to
a non-limiting embodiment or aspect of the present invention;
FIG. 15 is a sectional perspective view of the non-jacketed bullet
of FIG. 14;
FIG. 16 is a perspective view of a projectile tip according to a
non-limiting embodiment or aspect of the present invention; and
FIG. 17 is a sectional view of a sizing/forming press according to
a non-limiting embodiment or aspect of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Unless otherwise indicated, each numerical parameter in the
specification and claims should be construed in light of the number
of reported significant digits and by applying ordinary rounding
techniques. Also, it should be understood that any numerical range
recited herein is intended to include all sub-ranges subsumed
therein. For example, a range of "1 to 10" is intended to include
all sub-ranges between the recited minimum value of 1 and the
recited maximum value of 10. All compositions are given in weight
percent unless specifically stated otherwise.
It is to be understood that the invention may assume various
alternative variations and step sequences, except where expressly
specified to the contrary. It is also to be understood that the
specific products, systems, and processes illustrated in the
attached drawings, and described in the following specification,
are simply exemplary embodiments of the invention. Hence, specific
dimensions and other physical characteristics related to the
embodiments disclosed herein are not to be considered as limiting.
As used in the specification and the claims, the singular form of
"a", "an", and "the" include plural referents unless the context
clearly dictates otherwise.
The present invention is directed to a non-jacketed bullet. FIG. 1
illustrates a perspective view of a non-jacketed bullet according
to a non-limiting embodiment or aspect of the present invention,
and FIG. 2 illustrates a sectional perspective view of the
non-jacketed bullet of FIG. 1.
As illustrated in FIGS. 1 and 2, and in one non-limiting embodiment
or aspect, the non-jacketed bullet comprises a monolithic sintered
body 10. The monolithic sintered body 10 may include a base portion
12 having a proximal end 14 and a distal end 16 and a hollow nose
portion 18 extending distally from the distal end of the base
portion 12.
In one non-limiting embodiment or aspect, the base portion 12 may
include at least one transverse cross-section that is generally
symmetric with respect to the central longitudinal axis of rotation
L of the bullet. The cross-section may be circular. In another
non-limiting embodiment or aspect, the entire base portion 12 may
be generally symmetric with respect to the central longitudinal
axis of rotation L of the bullet to stabilize the trajectory of the
bullet.
In one non-limiting embodiment or aspect, a distal portion 20 of
the base portion 12 or the entire base portion 12 may be tapered
axially inwardly in a distally extending direction. As a result,
the transverse cross-sectional area of the base portion 12
decreases from the proximal end 14 of the base portion 12 to the
distal end 16 of the base portion 12.
In one non-limiting embodiment or aspect, the base portion 12 may
include at least one transverse cross section that is solid
throughout. In another non-limiting embodiment or aspect, the
entire base portion 12 may be solid throughout.
The hollow nose portion 18 comprises a proximal end 22, a distal
end 24, and a sidewall 26 extending between the proximal end 22 and
the distal end 24. The sidewall 26 defines at least one internal
cavity 28. The hollow nose portion 18 may be formed into the shape
of a hollow tapered nose such that the outer surface and/or the
inner surface of the sidewall 26 of the hollow nose portion 18
taper axially inwardly from the proximal end 22 to the distal end
24. As a result, the transverse cross-sectional area of the
internal cavity 28 decreases from the proximal end 22 of the hollow
nose portion 18, adjacent to the base portion 12, to the distal end
24 of the hollow nose portion 18 and the transverse cross-sectional
area defined by the outer perimeter of the hollow nose portion 18
decreases from the proximal end 22 of the hollow nose portion 18,
adjacent to the base portion 12, to the distal end 24 of the hollow
nose portion 18.
In one non-limiting embodiment or aspect, a portion of the hollow
nose portion 18 or the entire hollow nose portion 18 may include at
least one transverse cross-section that is generally symmetric with
respect to the central longitudinal axis of rotation L of the
bullet. In another non-limiting embodiment or aspect, the outer
surface of the hollow nose portion 18 may be symmetric with respect
to the central longitudinal axis of rotation L of the bullet to
stabilize the trajectory of the bullet.
In one non-limiting embodiment or aspect, the internal cavity 28 of
the hollow nose portion 18 may have a cylindrical transverse
cross-section. In another non-limiting embodiment or aspect, the
internal cavity 28 of the hollow nose portion 18 may have a
transverse cross-section that is at least partly polygonal. In yet
another non-limiting embodiment or aspect, the internal cavity 28
of the hollow nose portion 18 may have a transverse cross-section
that is at least partly triangular, square, hexagonal, or
octagonal. A triangular, square, or polygonal internal cavity 28
may facilitate the opening of the hollow nose portion 18 in
sections to form distinct petals upon expansion when entering a
target, such as tissue or simulated tissue. The internal cavity 28
of the hollow nose portion 18 may be configured and modified
depending on the intended use. For example, an internal cavity 28
having a smaller cross-section and shorter length may result in
deeper penetration and a smaller initial wound cavity. An internal
cavity 28 having a larger cross-section and longer length may
result in shorter penetration and a larger initial wound cavity. In
one non-limiting embodiment or aspect, the internal cavity 28 may
be generally symmetric with respect to the central longitudinal
axis of rotation L of the bullet to stabilize the trajectory of the
bullet.
In one non-limiting embodiment or aspect, as shown in FIG. 3, the
monolithic sintered body 110 may have an internal cavity comprising
a proximal portion 128a and a distal portion 128b. The proximal
portion 128a of the internal cavity 128 may extend distally from
the distal end 116 of the base portion 112 and the distal portion
128b of the internal cavity 128 may extend distally from the
proximal portion 128a. In one non-limiting embodiment or aspect,
the proximal portion 128a of the internal cavity 128 may have a
transverse cross-section that is circular forming a cylindrical
internal cavity 128, while the inner surface of the distal portion
128b may taper inwardly in a distal direction such that the
transverse cross-sectional area of the distal portion 128b of the
internal cavity 128 decreases as it approaches the distal end 124
of the hollow nose portion 118. The maximum transverse
cross-sectional area of the distal portion 128b of the internal
cavity 128 may be larger than the maximum transverse
cross-sectional area of the proximal portion 128a of the internal
cavity 128. In one non-limiting embodiment or aspect, the distal
portion 128b may first taper outwardly in a distal direction and
then taper inwardly in a distal direction.
In non-limiting embodiments or aspects, the wall thickness of the
sidewall of the hollow nose portion 18 may be less than half of a
maximum radius of the base portion 12, for example, less than a
third of the maximum radius of the base portion 12 or less than a
quarter of the maximum radius of the base portion 12. Thinner wall
thickness of the hollow tapered nose 18 may facilitate an opening
of the hollow tapered nose 18 upon expansion when entering a
target, such as tissue or simulated tissue.
In one non-limiting embodiment or aspect, the distal end 24 of the
hollow nose portion 18 may be open into the internal cavity 28 of
the hollow nose portion 18. In one non-limiting embodiment or
aspect, the opening may have a transverse cross-section having the
same shape as the cross-section of the internal cavity 28. The
opening may facilitate expansion (mushrooming) of the hollow nose
portion 18 on impact, increasing the diameter of the bullet to
limit penetration and/or produce a larger diameter wound for faster
incapacitation. In another non-limiting embodiment or aspect, the
distal end 24 of the hollow nose portion 18 may be closed.
In one non-limiting embodiment or aspect, the base portion 12 and
the hollow nose portion 18 of the monolithic sintered body 10 may
be integrally formed together during a sintering process that
applies heat and/or pressure to a compacted powder preform to form
a unitary mass of material that includes solid-solid interfaces
between adjacent powder particles. The monolithic nature of the
monolithic sintered body 10 may provide better rotational stability
compared to non-monolithic projectiles.
In one non-limiting embodiment or aspect, the hollow nose portion
18 may be tapered using a deformation process.
In one non-limiting embodiment or aspect, the material of the
monolithic sintered body 10 may be any material capable of being
sintered and deformed. In one non-limiting embodiment or aspect,
the material of the monolithic sintered body 10 may be lead-free.
In one non-limiting embodiment or aspect, the material of the
monolithic sintered body 10 may include at least one of copper,
nickel, tin, zinc, or combinations thereof. In one non-limiting
embodiment or aspect, the monolithic sintered body may be made from
copper or a copper-based alloy. In one non-limiting embodiment or
aspect, the copper-based alloy may include at least 60% copper, for
example, at least 70% copper, at least 80% copper, or at least 90%
copper. In another non-limiting embodiment or aspect, the
copper-based alloy may include at least one of nickel, tin, zinc,
or any combination thereof to activate desired toughness and
ductility. The ability to vary the mechanical properties via the
composition gives flexibility and versatility. For example, varying
the ductility can affect the depth of penetration of the bullet,
the expansion of the bullet, the fracture properties of the bullet
and/or the penetration of the bullet into various surfaces. In one
non-limiting embodiment or aspect, the material of the monolithic
sintered body 10 may be a lead-free copper-based alloy that
includes at least 70% copper and at least one of nickel, tin, zinc,
or any combination thereof. In one non-limiting embodiment or
aspect, the material of the monolithic sintered body 10 may be a
lead-free copper-based alloy that includes at least 70% copper and
the remainder zinc, for example, at least 80% copper and the
remainder zinc, at least 90% copper and the remainder zinc, or at
least 95% copper and the remainder zinc.
In one non-limiting embodiment or aspect, a method of manufacturing
an bullet includes providing a monolithic sintered body including a
base portion and a hollow peripheral portion extending distally
from the base portion and forming the hollow peripheral portion
into a hollow tapered nose.
FIG. 4A shows a perspective view of a monolithic sintered body 30
including a base portion 32 and a hollow peripheral portion 34
extending distally from the base portion 32 prior to forming the
hollow peripheral portion 34 into a hollow tapered nose according
to one non-limiting embodiment or aspect. FIG. 4B shows a sectional
perspective view of the monolithic sintered body 30 of FIG. 4A. The
hollow peripheral portion 34 has an internal cavity 33 having a
circular cross-section.
FIG. 5A shows a perspective view of a monolithic sintered body 130
including a base portion 132 and a hollow peripheral portion 134
extending distally from the base portion 132 prior to forming the
hollow peripheral portion 134 into a hollow tapered nose according
to one non-limiting embodiment or aspect. FIG. 5B shows a sectional
perspective view of the monolithic sintered body 130 of FIG. 5A.
The hollow peripheral portion 134 has an internal cavity 133 having
a triangular cross-section.
FIG. 6A shows a perspective view of a monolithic sintered body 230
including a base portion 232 and a hollow peripheral portion 234
extending distally from the base portion 232 prior to forming the
hollow peripheral portion 234 into a hollow tapered nose according
to one non-limiting embodiment or aspect. FIG. 6B shows a sectional
perspective view of the monolithic sintered body 230 of FIG. 6A.
The hollow peripheral portion 234 has an internal cavity 233 having
a square cross-section.
FIG. 7A shows a perspective view of a monolithic sintered body 330
including a base portion 332 and a hollow peripheral portion 334
extending distally from the base portion 332 prior to forming the
hollow peripheral portion 334 into a hollow tapered nose according
to one non-limiting embodiment or aspect. FIG. 7B shows a sectional
perspective view of the monolithic sintered body 330 of FIG. 7A.
The hollow peripheral portion 334 has an internal cavity 333 having
a hexagonal cross-section.
FIG. 8A shows a perspective view of a monolithic sintered body 430
including a base portion 432 and a hollow peripheral portion 434
extending distally from the base portion 432 prior to forming the
hollow peripheral portion 434 into a hollow tapered nose according
to one non-limiting embodiment or aspect. FIG. 8B shows a sectional
perspective view of the monolithic sintered body 430 of FIG. 8A.
The hollow peripheral portion 434 has an internal cavity 433 having
an octagonal cross-section.
In one non-limiting embodiment or aspect, a proximal portion of the
internal cavity of the hollow peripheral portion may extend
distally from the distal end of the base portion and a distal
portion of the internal cavity may extend distally from the
proximal portion. The proximal portion may have a different
transverse cross-sectional area and/or shape from the distal
portion. Each of the proximal portion and the distal portion may
have a transverse cross-section that is triangular, square,
hexagonal, or octagonal. The maximum transverse cross-sectional
area of the distal portion of the internal cavity may be larger
than the maximum transverse cross-sectional area of the proximal
portion of the internal cavity. The distal portion may have two
sections where the first section tapers outwardly in a distally
extending direction from the proximal portion 533a and the second
section has no taper.
In one non-limiting embodiment or aspect, the proximal portion may
have a transverse cross-section that is circular.
FIG. 9 shows a sectional view of a monolithic sintered body 530
including a base portion 532 and a hollow peripheral portion 534
extending distally from the base portion 532 prior to forming the
hollow peripheral portion 534 into a hollow tapered nose according
to one non-limiting embodiment or aspect. The proximal portion 533a
of the internal cavity 533 has a transverse cross-section that is
circular, while the transverse cross-section of the distal portion
533b of the internal cavity 533 is hexagonal. The maximum
transverse cross-sectional area of the distal portion 533b of the
internal cavity 533 is larger than the maximum transverse
cross-sectional area of the proximal portion 533a of the internal
cavity 533. The distal portion 533b has two sections where the
first section tapers outwardly in a distally extending direction
from the proximal portion 533a and the second section has no
taper.
In one non-limiting embodiment or aspect, a portion of the distal
end of the base portion 32 may have a constant outside diameter or
may taper axially inwardly in a distally extending direction.
In one non-limiting embodiment or aspect, the hollow peripheral
portion 34 may have an outer surface with a constant outside
diameter or an outer surface that tapers axially inwardly in a
distally extending direction.
In one non-limiting embodiment or aspect, the hollow peripheral
portion 34 may have an inner surface with a constant inside
diameter or an inner surface that tapers axially inwardly in a
distally extending direction.
In one non-limiting embodiment or aspect, the hollow peripheral
portion 34 may be formed into the shape of a hollow tapered nose by
a deformation process. In one preferred and non-limiting embodiment
or aspect, the entire hollow peripheral portion 34 may be formed
into the shape of a hollow tapered nose by a deformation process.
In one non-limiting embodiment or aspect, the hollow peripheral
portion 34 and a portion of the base portion 32 may be formed into
a hollow tapered nose, as shown in FIGS. 1 and 2, by a deformation
process.
In one non-limiting embodiment or aspect, the method of
manufacturing an bullet may include providing powder to a cavity
formed in a die between at least an upper punch and a lower punch
to form a compacted powder preform including a base portion and a
hollow peripheral portion extending distally from the base portion.
In one non-limiting embodiment or aspect, the powder may be any
material capable of being sintered and deformed. In one
non-limiting embodiment or aspect, the powder may be selected from
gas atomized powder or water atomized powder. In one non-limiting
embodiment or aspect, the powder may be lead free. In one
non-limiting embodiment or aspect, the powder may comprise at least
one of copper, nickel, tin, zinc, or combinations thereof. In one
non-limiting embodiment or aspect, the powder may comprise copper
or a copper-based alloy. In one non-limiting embodiment or aspect,
the copper-based alloy powder may include at least 60% copper, for
example, at least 70% copper, at least 80% copper, or at least 90%
copper. In another non-limiting embodiment or aspect, the
copper-based alloy powder may include at least one of nickel, tin,
zinc, or any combination thereof to activate desired toughness and
ductility. In one non-limiting embodiment or aspect, the powder may
comprise a lead-free copper-based alloy that includes at least 70%
copper and at least one of nickel, tin, zinc, or any combination
thereof. In one non-limiting embodiment or aspect, the lead-free
copper-based alloy that includes at least 70% copper and the
remainder zinc, for example, at least 80% copper and the remainder
zinc, at least 90% copper and the remainder zinc, or at least 95%
copper and the remainder zinc. As an example, the powder may be
water atomized Accu-powder 165A, which comprises 95% copper and a
remainder of zinc with a particle size of 20-100 .mu.m. The ability
to vary the mechanical properties via the composition gives
flexibility and versatility. For example, varying the ductility can
affect the depth of penetration of the bullet, the expansion of the
bullet, the fracture properties of the bullet, and/or the
penetration of the bullet into various surfaces.
Particle size of the constituent powder can be at least 5 .mu.m and
up to 500 .mu.m, for example, 5-500 .mu.m, 20-300 .mu.m, or 20-100
.mu.m.
In one non-limiting embodiment or aspect, the powder may be mixed
with a lubricant to allow the powder particles to move relative to
other particles and relative to tooling. For example, atomized wax
may be used, such as Acrawax A. At least 0.2 wt. % and up to 2.0
wt. % of the lubricant may be provided, for example, 0.2-2.0 wt. %,
0.2-1.0 wt. %, or 0.5 wt. %. The lubricant may be blended together
in a conical blender for 20 minutes to allow for
homogenization.
In one non-limiting embodiment or aspect, FIGS. 10 and 11 show
sectional views of tooling for forming a compacted powder preform.
The tooling may include a die 36, an upper punch 38, and a lower
punch 40, 140 having two sections. The die 36 may include an
internal through-hole 42 which may be cylindrical. The transverse
cross-sectional area of the through-hole 42 may be uniform. A lower
end of the upper punch 38 may have a size and shape corresponding
to a size and shape of an upper portion of the through-hole 42 of
the die 36 such that the lower end of the upper punch 38 can fit
into the through-hole 42 of the die 36 while not allowing powder to
pass between the die 36 and the upper punch 38. The size and shape
of the through-hole of the die 36 and the size and shape of the
lower end of the upper punch 38 may correspond to the desired size
and shape of the base portion of the compacted powder preform.
The first section 44 of the lower punch 40 may have a size and
shape corresponding to a size and shape of the lower portion of the
through-hole 42 of the die 36 such that the first section 44 of the
lower punch 40 can fit into the through-hole 42 of the die 36 while
not allowing powder to pass between the die 36 and the first
portion 44 of the lower punch 40. The second section 46 of the
lower punch 40 has a size and shape corresponding to the size and
shape of the internal cavity that is desired in the hollow
peripheral portion of the compacted powder preform. For example,
the second section 46 of the lower punch 40 has a transverse
cross-section that is triangular, square, hexagonal, or
octagonal.
In one non-limiting embodiment or aspect, the second section 46 of
the lower punch 40 may comprise two portions each having a
different transverse cross-sectional area and/or shape in order to
form a bullet having an internal cavity with two portions as
described above. Each of the first portion and the second portion
may have a transverse cross-section that is triangular, square,
hexagonal, or octagonal. The maximum transverse cross-sectional
area of the distal portion of the internal cavity may be larger
than the maximum transverse cross-sectional area of the proximal
portion of the internal cavity. The second portion may have two
sections where the first section tapers outwardly in a distally
extending direction from the first portion and the second section
has no taper.
In one non-limiting embodiment or aspect, FIG. 12 shows tooling
where the second section 146 of the lower punch 140 has portions.
The first portion 146a has a circular transverse cross-section and
the second portion 146b has a hexagonal transverse cross-section.
The second portion 146b includes a section that tapers outwardly in
a distally extending direction from the first portion 146a.
The first section 44 of the lower punch 40 and the second section
46 of the lower punch 40 may be separate from one another or may be
integral.
In one non-limiting embodiment or aspect shown in FIG. 10, the
second section 46 of the lower punch 40 passes through an internal
passageway 48 in the first section 44 of the lower punch 40 and
extends distally beyond the distal end of the first section 44 of
the lower punch 40. The second section 46 of the lower punch 40 has
a circular transverse cross-section forming a cylindrical internal
cavity in the hollow peripheral portion of the compacted powder
preform.
In another non-limiting embodiment or aspect shown in FIG. 11, the
second section 46 of the lower punch 40 is integral with the first
section 44 of the lower punch 40 and has a hexagonal transverse
cross-section forming an internal cavity having a hexagonal
transverse cross-section in the hollow peripheral portion of the
compacted powder preform as shown in FIGS. 7A and 7B.
In either embodiment or aspect, the sidewall of the hollow
peripheral portion of the compacted powder preform is formed
between the top surface of the first section 44 of the lower punch
40, the outer surface of the second section 46 of the lower punch
40, and the inner surface of the through-hole 42 of the die 36. The
base portion of the compacted powder preform is formed between the
bottom surface of the upper punch 38, the top surface of the second
portion 46 of the lower punch 40, and the inner surface of the
through-hole 42 of the die 36. In one non-limiting embodiment or
aspect, the first section 44 and the second section 46 of the lower
punch 40 may be separate pieces as shown in FIG. 10. In another
non-limiting embodiment or aspect, the first section 44 and the
second section 46 of the lower punch 40 may be integral as shown in
FIG. 11. In yet another non-limiting embodiment or aspect, the
second section 46 of the lower punch 40 may be in a sliding
relationship with the first section 44 of the lower punch 40.
In one non-limiting embodiment or aspect, the die 36 and the upper
punch 38 may be made of tool steel. In another non-limiting
embodiment or aspect, the die 36, the upper punch 38, and the lower
punch 40 may be made of tool steel.
In one preferred and non-limiting embodiment or aspect, the
through-hole 42 in the die 36 may be a cylindrical cavity.
To form the compacted powder preform, powder may be provided to the
cavity formed by the die 36, the bottom end of the upper punch 38,
and the top end of the lower punch 40, and at least the upper punch
38 may be pressed to compact the powder. In one preferred and
non-limiting embodiment or aspect, the powder may be compacted to
form the compacted powder preform by moving the upper punch 38
and/or the lower punch 40 into the through-hole 42 of the die 36
such that the powder is compacted between the upper punch 38 and
the lower punch 40. In one non-limiting embodiment or aspect, the
upper punch 38 may enter the die 36 and exert 20-60 tons per square
inch of pressure onto the powder. In one preferred and non-limiting
embodiment or aspect, the tooling may be placed in a uniaxial
compaction press such as a 30 ton Gasbarre mechanical press.
After compaction, the compacted powder preform (green preform) may
be ejected via the lower punch 40 and placed in a sintering
furnace.
In one preferred and non-limiting embodiment or aspect, the
compacted powder preform may be heated to a temperature below the
melting point of its main constituent for a time sufficient to form
and grow necks between adjacent powder particles such that
sufficient ductility is provided for a subsequent step where the
hollow peripheral portion and, optionally, a portion of the base
portion is deformed into the shape of a hollow tapered nose.
In one non-limiting embodiment or aspect, the time and temperature
of sintering may be adjusted to adjust the desired mechanical
properties of the bullet. In one non-limiting embodiment or aspect,
the sintering temperature may be at least 1500.degree. F. and at
most 2000.degree. F., for example, 1500-2000.degree. F.,
1600-2000.degree. F., or 1600-1950.degree. F. However, other
conditions, such as composition of the compacted powder preform,
may require sintering temperatures outside of 1500.degree. F. and
2000.degree. F. In one non-limiting embodiment or aspect, the
compact may be heated to a final sintering temperature of about
1900.degree. F. and held for about 60 minutes.
By way of non-limiting examples, Table 1 shows the sintering
temperatures for four brass powders comprising copper and zinc and
a copper powder.
TABLE-US-00001 TABLE 1 Copper (wt. %) Zinc (wt. %) Sintering
Temperature (.degree. F.) 70 30 1620 80 20 1670 90 10 1800 95 5
1900 100 0 1950
In one non-limiting embodiment or aspect, the compacted powder
preform may be sintered in a non-oxidizing or reducing atmosphere,
for example, a vacuum atmosphere or a gas atmosphere comprising
nitrogen, hydrogen, inert gases, or mixtures thereof.
In one non-limiting example, the compacted powder preform is
sintered in a belt feed sintering furnace with a controlled
temperature profile and reducing atmosphere. For example, an Abbott
furnace company 4 zone 20'' sintering furnace may be used. The
atmosphere may be a nitrogen-hydrogen mix with varied gas flows of
nitrogen and hydrogen at various points in the furnace.
In one preferred and non-limiting embodiment or aspect, the method
of manufacturing an bullet may include deforming the hollow
peripheral portion 34 of the monolithic sintered body 30 into the
shape of a hollow tapered nose and/or reduce the porosity of the
hollow peripheral portion 34, such as by a mechanical deformation
in a sizing/forming press.
In one non-limiting embodiment or aspect, a deformation process may
be further applied to the base portion 32 to shape the base portion
32 and/or to reduce porosity of the base portion 32.
According to one non-limiting embodiment or aspect, FIG. 13 shows a
sectional view of a sizing/forming press for forming the hollow
peripheral portion 34, and, optionally, a portion of the base
portion 32 into the shape of a hollow tapered nose. The
sizing/forming press may include a die 50 and a punch 52. The die
50 has an internal cavity 54 having a shape corresponding to the
desired shape of the final monolithic sintered body. In one
non-limiting embodiment or aspect, the die 50 may have a
cylindrical cavity with a tapered, generally conical end to give
the monolithic sintered body 30 its final shape, including a hollow
tapered nose portion, while retaining the internal cavity of the
monolithic sintered body 30.
The monolithic sintered body 30 is placed into the internal cavity
54 of the die 50 and the punch 52 is inserted into the internal
cavity 54 of the die, thereby forcing the monolithic sintered body
30 to deform and contour to the shape of the internal cavity 54 of
the die 50. The transverse cross-sectional area of the outer
surface of the hollow nose portion 18 is only minimally changed at
the proximal end 22, but is reduced significantly at the distal end
24, thereby closing or nearly closing the distal end 24 of the
hollow nose portion 18. The shape of the internal cavity 28 of the
hollow nose portion 18 after deformation is determined by the shape
of the hollow peripheral portion 34 of the monolithic sintered body
30 prior to forming. When the transverse cross-section of the
hollow peripheral portion 34 of the monolithic sintered body 30
prior to forming is triangular, square, hexagonal, or octagonal,
the inner surface of the hollow peripheral portion 34 folds
inwardly during the deformation such that the inner surface of the
internal cavity 28 of the monolithic sintered body 30 after
deformation may have portions that taper outwardly in a distal
direction and portions that taper inwardly in a distal direction.
The combination of the shape of the internal cavity 33 of the
hollow peripheral portion 34 and the deformation of the hollow
peripheral portion 34 provides a non-jacketed bullet having a
cavity with a unique shape that is larger than prior art
non-jacketed bullets.
In one non-limiting embodiment or aspect, the deformation of the
hollow peripheral portion 34 into the shape of a hollow tapered
nose restrikes the outside dimension and also forms the conical
nose (ogive) of the bullet while maintaining the internal hollow
cavity for increased expansion.
In one preferred and non-limiting embodiment or aspect, FIG. 13
further illustrates a holder 56 for holding the monolithic sintered
body 30 during insertion of the monolithic sintered body 30 and the
punch 52 into the die 50. In another non-limiting embodiment or
aspect, FIG. 13 further illustrates a pin 58 for facilitating the
release of the monolithic sintered body 30 from the die 50 after
forming the hollow peripheral portion 34 into the shape of a hollow
tapered nose.
After the monolithic sintered body 30 is released from the die 50,
the monolithic sintered body 30 may be deburred, such as by
vibratory or rotary deburring, to remove burrs, polish the edges,
and ready the bullet for loading into ammunition.
FIG. 14 illustrates a perspective view of a non-jacketed bullet
according to another non-limiting embodiment or aspect of the
present invention, and FIG. 15 illustrates a sectional perspective
view of the non-jacketed bullet of FIG. 14.
As illustrated in FIGS. 14 and 15, the non-jacketed bullet
comprises any of the monolithic sintered bodies 210 described above
and a projectile tip 60. The projectile tip 60, shown in FIG. 16,
may include a base portion 62 having a proximal end 64 and a distal
end 66 and a nose portion 68 extending distally from the distal end
66 of the base portion 62.
In one non-limiting embodiment or aspect, the base portion 62 may
be generally symmetric with respect to the central longitudinal
axis of rotation L of the bullet to stabilize the trajectory of the
bullet. The cross-section of the base portion 62 may be circular,
and the base portion 62 may have a substantially cylindrical
shape.
In one non-limiting embodiment or aspect, the base portion 62 may
include at least one transverse cross section that is solid
throughout. In another non-limiting embodiment or aspect, the
entire base portion 62 may be solid throughout.
The nose portion 68 comprises a proximal end 70 and a distal end
72. The nose portion 68 has a substantially conical shape such that
the outer surface of the nose portion 68 tapers axially inwardly
from the proximal end 70 to the distal end 72. As a result, the
transverse cross-sectional area of the nose portion 68 decreases
from the proximal end 70 of the nose portion 68, adjacent to the
base portion 62, to the distal end 72 of the nose portion 68.
In one non-limiting embodiment or aspect, the base portion 62 of
the projectile tip 60 may be integrally formed together during a
sintering process that applies heat and/or pressure to a compacted
powder preform to form a unitary mass of material.
In one non-limiting embodiment or aspect, the material of the
projectile top 60 may be any material capable of being sintered and
deformed. In one non-limiting embodiment or aspect, the material of
the projectile tip 60 may be lead-free. In one non-limiting
embodiment or aspect, the material of the projectile tip 60 may
include iron and at least one of carbon, molybdenum, and copper. In
one non-limiting embodiment or aspect, the iron-based alloy may
include at least 60% iron, for example, at least 90% iron or at
least 95% iron. In another non-limiting embodiment or aspect, the
iron-based alloy may include up to 5% carbon, for example, up to
0.75% carbon. While no carbon need be added to the iron-based
alloy, in one non-limiting embodiment or aspect, at least 0.5%
carbon may be added, for example, at least 0.3% carbon. The iron
based alloy may include 0-.5% carbon or 0.3-0.75% carbon. While no
additional alloying elements need be added to the iron-based alloy,
in one non-limiting embodiment or aspect, at least 0.8% molybdenum
and up to 0.9% molybdenum, for example, 0.8-0.9% molybdenum or
0.85% molybdenum may be included in the iron-based alloy and/or at
least 1.5% copper and up to 2.5% copper, for example, 1.5-2.5%
copper, 1.75-2.25% copper, or 2% copper may be included in the
iron-based alloy. In one non-limiting embodiment or aspect, the
material of the projectile tip 60 may be an iron-based alloy that
includes 95% iron and the remainder carbon, for example, at least
97.5% iron and the remainder carbon, or at least 99% iron and the
remainder carbon.
In one non-limiting embodiment or aspect, the method of
manufacturing a bullet may include providing powder to a cavity
formed in a die between at least an upper punch and a lower punch
to form a compacted powder preform. In one non-limiting embodiment
or aspect, the powder may be any material capable of being sintered
and deformed. In one non-limiting embodiment or aspect, the powder
may be selected from gas atomized powder or water atomized powder.
In one non-limiting embodiment or aspect, the powder may be
lead-free. In one non-limiting embodiment or aspect, the powder may
be an iron-based alloy powder comprising iron and at least one of
carbon, molybdenum, and copper. In one non-limiting embodiment or
aspect, the iron-based alloy powder may include at least 60% iron,
for example, at least 95% iron, at least 97.5% iron, or at least
99% iron. In another non-limiting embodiment or aspect, the
iron-based alloy powder may include at least one of molybdenum or
copper. In one non-limiting embodiment or aspect, the lead-free
iron-based alloy powder may include at least 95% iron and the
remainder carbon, for example, at least 97.5% iron and the
remainder carbon or at least 99% iron and the remainder carbon. In
another non-limiting embodiment or aspect, an iron or iron-alloy
powder may be mixed with a carbon powder, such as graphite.
Particle size of the constituent iron or iron-based alloy powder
can be at least 10 .mu.m and up to 300 .mu.m, for example, 10-300
.mu.m, 10-100 .mu.m, or 20-100 .mu.m. Particle size of the
constituent carbon powder can be at least 0.5 .mu.m and up to 100
.mu.m, for example, 0.5-100 .mu.m, 1-5 .mu.m, or 1 .mu.m.
In one non-limiting embodiment or aspect, the powder may be mixed
with a lubricant to allow the powder particles to move relative to
other particles and relative to tooling. For example, atomized wax
may be used, such as Acrawax A. At least 0.25% and up to 5.0% of
the lubricant may be provided, for example, 0.25-5.0%, 0.3-0.75%,
or 0.5%. The lubricant and the powder may be blended together in a
conical blender for 20 minutes to allow for homogenization.
In one non-limiting embodiment or aspect, a compacted powder
preform having the final desired shape is formed from the powder in
a similar manner to the compacted powder preform for the body of
the bullet that is described above.
In one preferred and non-limiting embodiment or aspect, the
compacted powder preform may be heated to a temperature below the
melting point of its main constituent for a time sufficient to form
and grow bonds between adjacent powder particles.
In one non-limiting embodiment or aspect, the time and temperature
of sintering may be adjusted to adjust the desired mechanical
properties of the bullet. In one non-limiting embodiment or aspect,
the sintering temperature may be at least 1400.degree. F. and at
most 2600.degree. F., for example, 1400-2600.degree. F.,
1900-2300.degree. F., or 2050.degree. F. However, other conditions,
such as composition of the compacted powder preform, may require
sintering temperatures outside of 1400.degree. F. and 2600.degree.
F.
In one non-limiting embodiment or aspect, the sintering time may be
at least 10 minutes and up to 60 minutes, for example, 10-60
minutes, 20-60 minutes, or 45 minutes.
In one non-limiting embodiment or aspect, the compacted powder
preform may be sintered in a non-oxidizing or reducing atmosphere,
for example, a vacuum atmosphere or a gas atmosphere comprising
nitrogen, hydrogen, inert gases, or mixtures thereof. The sintering
atmosphere may be 100 vol. % hydrogen or may be a hydrogen/nitrogen
mixture with at least 25 vol. % hydrogen, for example, 25-50 vol. %
hydrogen and 50-75 vol. % nitrogen or 25 vol. % hydrogen and 75
vol. % nitrogen.
In one non-limiting example, the compacted powder preform is
sintered in a belt feed sintering furnace with a controlled
temperature profile and reducing atmosphere. For example, an Abbott
furnace company 4 zone 20'' sintering furnace may be used.
In one preferred and non-limiting embodiment or aspect, the method
of manufacturing an bullet may include inserting the sintered
projectile tip 60 into the internal cavity 33 of the undeformed
monolithic sintered body 30 and deforming the hollow peripheral
portion 34 of the monolithic sintered body 30 into the shape of a
hollow tapered nose and/or reducing the porosity of the hollow
peripheral portion 34, such as by a mechanical deformation in a
sizing/forming press.
In one non-limiting embodiment or aspect, a deformation process may
be further applied to the base portion 32 to shape the base portion
32 and/or to reduce porosity of the base portion 32.
According to one non-limiting embodiment or aspect, FIG. 17 shows a
sectional view of a sizing/forming press for forming the hollow
peripheral portion 34, and, optionally, a portion of the base
portion 32 of the monolithic sintered body 30 into the shape of a
hollow tapered nose. In FIG. 17, the bullet is being removed from
the sizing/forming press after deformation. The sizing/forming
press may include a die 150, a pin 158, and a punch 152. The die
150 has an internal cavity 154 having a shape corresponding to the
desired shape of the final bullet. In one non-limiting embodiment
or aspect, the die 150 may have a cylindrical cavity with a
tapered, generally conical end to give the monolithic sintered body
30 its final shape, including a hollow tapered nose portion, while
sealing the projectile tip 60 within the internal cavity 33 of the
monolithic sintered body 30.
The monolithic sintered body 30 is deformed in the sizing/forming
press in the same manner as was described above with respect to the
bullet that does not include a projectile tip.
With respect to the sintering of both the monolithic sintered body
and the penetrator tip, in one non-limiting embodiment or aspect,
the sintering step is a liquid phase sintering process. The liquid
phase sintering process can be performed at a temperature at least
above the solidus of one of the materials. In one contemplated
liquid phase sintering process, the performed monolithic body or
the preformed penetrator top comprise at least two metallic
components (e.g., formed from a mixture of blended metallic powders
as described above), bonding occurs as the temperature is elevated
above the eutectic temperature of two materials and a temporary
liquid is formed. As soon as the liquid forms, it alloys with the
other metal and the melting point rises such that there is no
longer liquid. The result is light metal-to-metal bonding that
relies on the small, weak, and brittle intermetallic compounds that
form at the contact points of the particles as a result of passing
through the eutectic temperature.
In one non-limiting embodiment or aspect, a solid state sintering
process may be used. For example, a solid state sintering process
can be used for a bullet made of pre-alloyed materials or elemental
materials. In one embodiment of the solid state sintering process,
the sintering process occurs at a temperature below the solidus of
the constituent materials. Specifically, particles form bonds along
the regions that have been forced into close contact during
pressing or compacting of these particles. Bonding occurs by atoms
moving into the vacancies between particle boundaries. However, the
particles are essentially the same size and shape before and after
the sintering process. Dimensional changes of the compacted mixture
are small. In addition, no liquid metal is present at any stage
during the solid state sintering process. During the solid state
sintering process, neutral or slightly reducing atmospheres can be
used, since the oxide layer on the outside of the powdered
particles is mechanically smeared during the pressing operation
which prepares the metal in these regions for sinter bonding.
In one non-limiting embodiment or aspect, the bullet, either with
or without a penetrator tip, may have a porosity of between about 2
to about 20%. For example, in the green state, the compacted powder
preform may have a porosity of about 20%. In the sintered state,
the monolithic sintered body may have a porosity of about 10-15%.
After deformation, the bullet may have a porosity of about 5-10%.
It is believed that, as the monolithic sintered body is deformed,
large pores may collapse and the density of the part may increase.
The porosity allows the bullet to deform as it contacts the
engraved grooves in the barrel of the firearm. Conversely, when
jacketed bullets are used, material is removed by engraved grooves
in the barrel of the firearm.
In one non-limiting embodiment or aspect, ammunition is provided,
which may include a non-jacketed bullet according to one or more
embodiments or aspects described above and a cartridge casing
holding the non-jacketed bullet. In another non-limiting embodiment
or aspect, the ammunition may further include a priming compound
and/or gunpowder.
Although the invention has been described in detail for the purpose
of illustration based on what is currently considered to be the
most practical and preferred embodiments, it is to be understood
that such detail is solely for that purpose and that the invention
is not limited to the disclosed embodiments, but, on the contrary,
is intended to cover modifications and equivalent arrangements that
are within the spirit and scope of the description. For example, it
is to be understood that the present invention contemplates that,
to the extent possible, one or more features of any embodiment can
be combined with one or more features of any other embodiment.
* * * * *